Given that the DIY ethos is alive and well in the FOAMed world , I thought I would construct my own. There are lots of DIY training phantominstructions using gelatine. From my microbiology days I am more familiar with agar and with plenty of Asian grocers near by a quick trip gave a pack of agar. I used 11grams of dried agar to 900mL of hot water, boiled for two minutes until all agar threads had dissolved.

A marble into the bottom of an old yoghurt pot and the hot agar poured over. Thirty minutes later the agar had solidified to a block I could turn out and take some pictures. Ten days on now and the agar block is still solid with no bacterial growth.

Horizontal dimensions were perfect, 16mm by the US calipers which corresponded to 16mm on the handheld vernier calipers. Depth with the US was 61mm and with the verniers 63mm. So certainly although old, still accurate.